/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
#ifndef DateMath_h
#define DateMath_h

#include <math.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <wtf/CurrentTime.h>
#include <wtf/Noncopyable.h>
#include <wtf/text/WTFString.h>

namespace WTF {

enum TimeType {
    UTCTime = 0,
    LocalTime
};

struct LocalTimeOffset {
    LocalTimeOffset()
        : isDST(false)
        , offset(0)
    {
    }

    LocalTimeOffset(bool isDST, int offset)
        : isDST(isDST)
        , offset(offset)
    {
    }

    bool operator==(const LocalTimeOffset& other)
    {
        return isDST == other.isDST && offset == other.offset;
    }

    bool operator!=(const LocalTimeOffset& other)
    {
        return isDST != other.isDST || offset != other.offset;
    }

    bool isDST;
    int offset;
};

void initializeDates();
int equivalentYearForDST(int year);

// Not really math related, but this is currently the only shared place to put these.
WTF_EXPORT_PRIVATE double parseES5DateFromNullTerminatedCharacters(const char* dateString);
WTF_EXPORT_PRIVATE double parseDateFromNullTerminatedCharacters(const char* dateString);
WTF_EXPORT_PRIVATE double parseDateFromNullTerminatedCharacters(const char* dateString, bool& haveTZ, int& offset);
WTF_EXPORT_PRIVATE double timeClip(double);
// dayOfWeek: [0, 6] 0 being Monday, day: [1, 31], month: [0, 11], year: ex: 2011, hours: [0, 23], minutes: [0, 59], seconds: [0, 59], utcOffset: [-720,720]. 
String makeRFC2822DateString(unsigned dayOfWeek, unsigned day, unsigned month, unsigned year, unsigned hours, unsigned minutes, unsigned seconds, int utcOffset);

inline double jsCurrentTime()
{
    // JavaScript doesn't recognize fractions of a millisecond.
    return floor(WTF::currentTimeMS());
}

const char* const weekdayName[7] = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
const char* const monthName[12] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
const char* const monthFullName[12] = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };

const double hoursPerDay = 24.0;
const double minutesPerHour = 60.0;
const double secondsPerMinute = 60.0;
const double msPerSecond = 1000.0;
const double msPerMonth = 2592000000.0;
const double secondsPerHour = secondsPerMinute * minutesPerHour;
const double secondsPerDay = secondsPerHour * hoursPerDay;
const double msPerMinute = msPerSecond * secondsPerMinute;
const double msPerHour = msPerSecond * secondsPerHour;
const double msPerDay = msPerSecond * secondsPerDay;

WTF_EXPORT_PRIVATE bool isLeapYear(int year);

// Returns the number of days from 1970-01-01 to the specified date.
WTF_EXPORT_PRIVATE double dateToDaysFrom1970(int year, int month, int day);
WTF_EXPORT_PRIVATE int msToYear(double ms);
WTF_EXPORT_PRIVATE double msToDays(double ms);
WTF_EXPORT_PRIVATE int msToMinutes(double ms);
WTF_EXPORT_PRIVATE int msToHours(double ms);
WTF_EXPORT_PRIVATE int dayInYear(int year, int month, int day);
WTF_EXPORT_PRIVATE int dayInYear(double ms, int year);
WTF_EXPORT_PRIVATE int monthFromDayInYear(int dayInYear, bool leapYear);
WTF_EXPORT_PRIVATE int dayInMonthFromDayInYear(int dayInYear, bool leapYear);

// Returns combined offset in millisecond (UTC + DST).
WTF_EXPORT_PRIVATE LocalTimeOffset calculateLocalTimeOffset(double utcInMilliseconds, TimeType = UTCTime);

} // namespace WTF

using WTF::isLeapYear;
using WTF::dateToDaysFrom1970;
using WTF::dayInMonthFromDayInYear;
using WTF::dayInYear;
using WTF::minutesPerHour;
using WTF::monthFromDayInYear;
using WTF::msPerDay;
using WTF::msPerHour;
using WTF::msPerMinute;
using WTF::msPerSecond;
using WTF::msToYear;
using WTF::msToDays;
using WTF::msToMinutes;
using WTF::msToHours;
using WTF::secondsPerDay;
using WTF::secondsPerMinute;
using WTF::parseDateFromNullTerminatedCharacters;
using WTF::makeRFC2822DateString;
using WTF::LocalTimeOffset;
using WTF::calculateLocalTimeOffset;

#endif // DateMath_h
